For a transmitter of radio communication, a power amplifier is used to transmit radio waves in air. The power amplifier needs to output a signal of large power and is therefore a block consuming large power in the transmitter. Therefore, it is important to increase the power efficiency of the power amplifier to decrease the power consumption.
There are known linear mode power amplifier that receives supply of a power supply voltage based on an amplitude signal of an input signal and amplifies the input signal, and power amplifier that receives supply of a power supply voltage based on an amplitude signal of an input signal and amplifies a phase signal of the input signal (refer to, for example, the following Non-Patent Document 1).
Further, there is a known voltage control power amplifier that controls a drain voltage of a field effect transistor according to the envelope of an input signal and includes an envelope detection unit that detects the envelope of the input signal, a voltage control unit that controls the drain voltage according to the envelope of the input signal, and a feedback control unit that compares the envelope of the input signal and the drain voltage and controls the voltage control unit to make the error between them to zero (refer to, for example, the following Patent Document 1).    Patent Document 1: Japanese Laid-open Patent Publication No. 2003-179444